This invention relates to a power transmission including an annular speed selector which functions as a result of the resistance which it encounters. More particularly, the present invention utilizes the precession force of a gyroscope, which is an inertia wheel usually rotated at a high angular velocity.
In accordance with the invention, the power transmission shaft is divided into a drive guide shaft and a driven receiver shaft coaxial with the drive guide shaft, the two shafts having facing ends spaced axially from each other. This spacing provides a free space for mounting a universal joint which interconnects the inner end of the drive guide shaft to a first end of a secondary shaft which extends at an angle to the common axis of the drive and driven shafts. The axes of symmetry of all three shafts intersect at the geometrical center of the universal joint. The universal joint can be a ball and socket joint, a gimbal or any other type of universal joint which will transmit exactly, and without stress, rubbing or friction, the angular speed of the drive guide shaft as deflected at an angle through the secondary shaft extending at an angle to the common axis of the drive and driven shafts.
The universal joint, which may be of any suitable type, must be homokinetic and maintain unchanged the position of the point of intersection of the axes of symmetry of the three shafts. A cup-shaped support is secured to or is integral with the driven receiver shaft, and a frusto-conical ring gear is formed integrally of the internal surface of the periphery of the support. This ring gear meshes with a frusto-conical pinion which is formed integrally with the secondary shaft intermediate the ends of the latter. The cup-shaped support has a spacer mounted or seated therein and formed with an annular channel in which there is engaged a roller rotatable on the opposite end of the secondary shaft. This arrangement allows constant positioning of the parts providing for the free rotation of the receiver shaft and the secondary shaft.
The spacer may be a part separate from the support, or may be integral therewith. A counterweight, in the form of a bell-shaped member having a thickened rim, is secured to or is integral with the end of the secondary shaft adjacent the common axis of the drive and driven shaft.
The spacer has an annular track which is coaxial with the axis of summetry of the driven receiver shaft, and the free end of the secondary shaft revolves around the common axis of the drive and driven shafts. The annular track may be formed in a separate spacer or may be cut into the "bottom" of the cup-shaped support. The purpose of the annular track is to maintain the angle between the common axis of the drive and driven shafts and the axis of the secondary shaft at a constant value. Under these conditions, the secondary shaft revolves around the axis of symmetry of the drive guide shaft, describing a conical surface of revolution whose apex is at the geometrical center of the universal joint.
The inertia device may be in the form of a bell which is integral with the secondary shaft and has a thickened rim, and the center of gravity of all of the parts is at the intersection of the axes of symmetry of the three shafts at the geometrical center of the universal joint. This obtains the necessary static and dynamic equilibrium of the transmission, first by the fact that the center of gravity is symmetrical with the secondary shaft and second by the fact that the center of gravity is divided into two parts by an imaginary perpendicular plane passing through the common axis of the guide and receiver shafts and perpendicular to a plane which passes through the angle of diversion of the drive shaft and the secondary shaft.